Measurement of the Glutathione Redox Potentials in Membraneless Organelles

Glutathione (GSH) is essential for cellular redox regulation; however, the redox potential (E _GSH ) of the nucleus and membraneless organelles (MLOs) remains poorly understood. Here, we use the Grx1–roGFP2 sensor to measure the E _GSH of the nucleus and several MLOs such as the nucleoli, stress granules, p-bodies, paraspeckles, and Cajal bodies. Unlike suggested by previous findings, we found that nuclear E _GSH is stable throughout the cell cycle and identical to the cytosolic E _GSH , and the E _GSH of MLOs mirrors their surrounding environment. These findings challenge existing paradigms and provide novel insights into redox homeostasis across subcellular compartments.